Biological samples can be analyzed by illuminating the biological sample with a beam of light and detecting the scattered light. In order to be able to detect a presence or absence of a particular biological specimen or molecule, for instance DNA, RNA, cells and antibodies, of the biological sample the fluorescence method is useful. The fluorescence method utilizes labeling agents that are capable of binding to particular sites of a molecule of the biological sample. When the sample is illuminated with a beam of light the labeling agent will emit light at a wavelength different from the wavelength of the illumination beam.
By utilizing the capability of specific target molecules from the sample to be analyzed to bond to corresponding probe molecules, that for instance are present in a detection system, the presence or absence of the specific target molecule can be determined. For instance, if the target molecules are labeled with a labeling agent, and if the target molecules subsequently bind to a probe molecule, the presence of the target molecule can be verified if fluorescent light is detected. Examples of such target-probe molecule pairs are antibody-antigen, cell-antibody combinations and receptor-ligands pairs. Further examples include bonding or hybridization of for instance DNA-DNA pairs, RNA-RNA pairs and DNA-RNA hybrids.
In order to detect the emitted light from the labeling agent, the detection system must be capable of detecting radiation having a particular wavelength of emitted radiation originating from the labeled agents. This is a problem since the biological sample typical will emit light both having the wavelength of the illumination light and the emitted light from the labeling agents. Accordingly, a method capable of discriminating between the wavelengths of the illumination light and the emitted light from the labeling agents would be advantageous.
At the same time it would be beneficial to have a simple method for discriminating between the wavelengths of the illumination light and the emitted light.
U.S. Pat. No. 6,867,420 discloses a miniaturized optical excitation and detector system for detecting fluorescently labeled analytes in electrophoretic microchips and microarrays. The system uses miniature integrated components, light collection, optical fluorescence filtering, and an amorphous a-Si:H detector for detection. The collection of light is accomplished with proximity gathering and/or a micro-lens system. Optical filtering is accomplished by integrated optical filters. U.S. Pat. No. 6,867,420 discloses a detection system where the emitted light it filtered by an integrated optical filter and detected with a photo detector. However, the detection system in U.S. Pat. No. 6,867,420 is not simple.
Hence, an improved detection system would be advantageous, and in particular a more efficient and/or reliable detection system would be advantageous.